This invention relates to an electronic timepiece including a system for compensating for the variation in a frequency of a time reference signal with a temperature by using a temperature signal generator. The electronic timepiece includes a time reference signal generator and means for forming a time count unit signal from the time reference signal. A time counting mechanism is provided for keeping a time by using the time count unit signal and a time display mechanism is provided for displaying the time kept in the time counting mechanism.
The frequency of a time reference signal should essentially be kept in the restricted range even when the temperature of the surroundings of the timepiece is varied.
The specific resonance frequency must be changed with the external temperature even in a crystal oscillator which is used as a reference oscillator for a time reference signal generator used in high accuracy timepieces.
In order to overcome the problems of variations in the resonance frequency, the prior art includes several approaches. For example, with measurement equipment, a time reference signal generator is placed in a constant temperature vessel. With another approach, the frequency of an output is maintained by counterbalancing the thermal characteristics of the crystal oscillator to the temperature-capacity characteristic of a temperature sensing element thereby changing continuously the capacity of the time reference signal generator.
The first prior art approach has problems in that large amounts of electric power are consumed and a large space is required. Furthermore, with the second approach, it is difficult to find a temperature compensating element which has a temperature-capacity characteristic corresponding to that of the reference oscillator which is somewhat complex. In addition many types of temperature compensating elements do not have sufficient durability and stability and there are difficulties in forming an integrated circuit of the temperature compensating system.